TETRA (Terrestrial Trunked Radio) (formerly known as Trans-European Trunked Radio) communication networks and other communications networks generally provide for a trunked mode of operation and a direct mode of operation for communication between mobile stations. In current implementations of such communication networks, every mobile station receives every communication transmitted on its current channel which it is capable to detect, regardless of whether the communication is intended for that particular mobile station. While receiving an unwanted (or “alien”) communication, a mobile station is inhibited from receiving and/or transmitting other communications. Further, the mobile station radio transmitting the unwanted communication is unaware that it is blocking the channel.
Accordingly, there is a need for methods and devices of sub-group communication in a direct mode of operation.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.